My mother, ere she bore her son, This boon from Viśvakarmá won: “O Mandarí, thy child shall be In skill and glory next to me.” But why unbidden should I fill Thine ear with praises of my skill? Command the Vánar hosts to lay Foundations for the bridge to-day.”

In plain words: Nala explains that before he was born, Vishvakarma promised his mother Mandari her son would be almost as skilled as him. Then Nala stops praising himself and asks Rama to order the monkeys to start building the bridge today.